U.S. patent application number 16/281406 was filed with the patent office on 2020-05-14 for frequency-based communication system and method.
The applicant listed for this patent is General Electric Company. Invention is credited to Stephen Francis Bush, Guillaume Mantelet.
Application Number | 20200154452 16/281406 |
Document ID | / |
Family ID | 70552206 |
Filed Date | 2020-05-14 |
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United States Patent
Application |
20200154452 |
Kind Code |
A1 |
Bush; Stephen Francis ; et
al. |
May 14, 2020 |
FREQUENCY-BASED COMMUNICATION SYSTEM AND METHOD
Abstract
A communication system includes multiple nodes of a
time-sensitive network and a scheduler device. At least one of the
nodes is configured to obtain a first signal that is represented in
a frequency domain by multiple frequency components. The scheduler
device generates a schedule for transmission of signals including
the first signal within the time-sensitive network. The schedule
defines multiple slots assigned to different discrete frequency
sub-bands within a frequency band. The slots have designated
transmission intervals. The nodes are configured to transmit the
first signal through the time-sensitive network to a listening
device such that the first signal is received at the listening
device within a designated time window according to the schedule.
At least some of the frequency components of the first signal are
transmitted through the time-sensitive network within different
slots of the schedule based on the frequency sub-bands assigned to
the slots.
Inventors: |
Bush; Stephen Francis;
(Niskayuna, NY) ; Mantelet; Guillaume; (Oakbank,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
General Electric Company |
Schenectady |
NY |
US |
|
|
Family ID: |
70552206 |
Appl. No.: |
16/281406 |
Filed: |
February 21, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62758791 |
Nov 12, 2018 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04L 5/00 20130101; H04W
72/12 20130101; H04W 72/1263 20130101; H04W 72/044 20130101 |
International
Class: |
H04W 72/12 20060101
H04W072/12; H04W 72/04 20060101 H04W072/04 |
Claims
1. A communication system comprising: a scheduler device including
one or more processors configured to generate a schedule for
communication of signals through nodes of a time-sensitive network
that are communicatively connected to each other via links of the
time-sensitive network, at least a first signal of the signals
represented in a frequency domain by multiple frequency components
and received into the time-sensitive network from a publishing
device, wherein the one or more processors are configured to
generate the schedule by assigning multiple slots having designated
transmission intervals to different discrete frequency sub-bands
within a frequency band, wherein the schedule is generated to
direct the nodes to communicate the first signal from the
publishing device through the time-sensitive network to a listening
device such that the first signal is received at the listening
device within a designated time window according to the schedule,
wherein at least some of the frequency components of the first
signal are transmitted through the time-sensitive network based on
the frequency sub-bands assigned to the slots.
2. The communication system of claim 1, wherein the one or more
processors are configured to generate the schedule to direct the
nodes to transmit a first frequency component of the first signal
within a first slot of the slots that is assigned to a frequency
sub-band that contains a frequency of the first frequency
component, and to transmit a second frequency component of the
first signal within a second slot of the slots that is assigned to
a different frequency sub-band that contains a frequency of the
second frequency component.
3. The communication system of claim 1, wherein the one or more
processors are configured to determine a designated signal fidelity
target that represents a degree of correspondence between an exit
state of the first signal exiting the time-sensitive network at the
listening device and an entry state of the first signal entering
the time-sensitive network at the publishing device, wherein the
one or more processors are configured to generate the schedule to
assign the slots to at least a number of the frequency sub-bands
associated with the designated signal fidelity target.
4. The communication system of claim 3, wherein the one or more
processors are configured to generate the schedule based on the
designated signal fidelity target without utilizing a frame size
limit or a periodic latency limit as a constraint to the
schedule.
5. The communication system of claim 1, wherein the one or more
processors are configured to generate the schedule to assign less
than all the frequency sub-bands of the frequency band to the
slots, wherein the nodes are configured to filter out one or more
of the frequency components of the first signal having a frequency
outside of the frequency sub-bands by transmitting only the
frequency components of the first signal having frequencies within
the frequency sub-bands assigned to the slots.
6. The communication system of claim 1, wherein the one or more
processors are configured to generate the schedule to stagger the
transmission intervals of the slots such that a first frequency
component of the first signal within a first slot is transmitted by
the nodes of the time-sensitive network according to the schedule
at different times than the nodes transmit a second frequency
component of the first signal within a second slot.
7. The communication system of claim 1, wherein the frequency
components of the first signal are encoded within Ethernet frames,
the Ethernet frames including data representing one or more of a
frequency, an amplitude, or a phase of each of the frequency
components encoded therein.
8. The communication system of claim 1, wherein the first signal is
one or more of an audio signal, an ultrasound signal, a vibration
signal, an audible sound signal, or an infrasound signal.
9. The communication system of claim 1, wherein the one or more
processors are configured to generate or modify the schedule by
changing a size of the frequency sub-band assigned to one or more
of the slots after the first signal is transmitted through the
time-sensitive network.
10. A method comprising: generating a schedule for transmission of
signals within a time-sensitive network, wherein the schedule
defines multiple slots assigned to different discrete frequency
sub-bands within a frequency band, the slots having designated
transmission intervals; obtaining a first signal of the signals
from a publishing device, the first signal represented in a
frequency domain by multiple frequency components; and transmitting
the first signal through the time-sensitive network to a listening
device such that the first signal is received at the listening
device within a designated time window according to the schedule,
wherein at least some of the frequency components of the first
signal are transmitted through the time-sensitive network within
different slots of the schedule based on the frequency sub-bands
assigned to the slots.
11. The method of claim 10, wherein transmitting the first signal
through the time-sensitive network includes transmitting a first
frequency component of the first signal within a first slot of the
schedule assigned to a frequency sub-band that contains a frequency
of the first frequency component, and transmitting a second
frequency component of the first signal within a second slot of the
schedule assigned to a different frequency sub-band that contains a
frequency of the second frequency component.
12. The method of claim 10, further comprising: obtaining a
designated signal fidelity target that represents correspondence
between an exit state of the first signal exiting the
time-sensitive network at the listening device and an entry state
of the first signal entering the time-sensitive network at the
publishing device, wherein generating the schedule comprises
assigning the slots to a sufficient number of the frequency
sub-bands to satisfy the designated signal fidelity target.
13. The method of claim 12, wherein the schedule is generated based
on the designated signal fidelity target without utilizing a frame
size limit or a periodic latency limit as a constraint on the
schedule.
14. The method of claim 10, wherein the frequency sub-bands
assigned to the slots defined by the schedule represent less than
an entirety of the frequency band, wherein transmitting the first
signal comprises transmitting only the frequency components of the
first signal having frequencies within the frequency sub-bands
assigned to the slots to filter out one or more of the frequency
components of the first signal having a frequency outside of the
frequency sub-bands.
15. The method of claim 10, wherein generating the schedule
comprises staggering the transmission intervals of the slots such
that a first frequency component of the first signal within a first
slot is transmitted by the nodes of the time-sensitive network
according to the schedule at different times than the nodes
transmit a second frequency component of the first signal within a
second slot.
16. The method of claim 10, wherein the frequency components of the
first signal are encoded within Ethernet frames, the Ethernet
frames including data representing one or more of a frequency, an
amplitude, or a phase of each of the frequency components encoded
therein.
17. The method of claim 10, wherein the first signal is one or more
of an audio signal, an ultrasound signal, a vibration signal, an
audible sound signal, or an infrasound signal.
18. The method of claim 10, further comprising: combining the
frequency components of the first signal after transmitting the
frequency components through the time-sensitive network to provide
an intact first signal to the listening device.
19. A communication system comprising: a scheduler device including
one or more processors configured to generate a schedule for
communication of signals through nodes of a time-sensitive network
that are communicatively connected to each other via links of the
time-sensitive network, at least a first signal of the signals
represented in a frequency domain by multiple frequency components
and received into the time-sensitive network from a publishing
device, wherein the one or more processors are configured to
generate the schedule by assigning multiple slots having designated
transmission intervals to different discrete frequency sub-bands
within a frequency band, wherein the schedule is generated to
direct the nodes to communicate the frequency components of the
first signal through the time-sensitive network based on the
frequency sub-bands assigned to the slots such that the nodes
transmit a first frequency component of the first signal within a
first slot of the slots that is assigned to a frequency sub-band
that contains a frequency of the first frequency component and the
nodes transmit a second frequency component of the first signal
within a second slot of the slots that is assigned to a different
frequency sub-band that contains a frequency of the second
frequency component.
20. The communication system of claim 19, wherein the one or more
processors are configured to generate or modify the schedule by
changing a size of the frequency sub-band assigned to one or more
of the slots after the first signal is transmitted through the
time-sensitive network.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional
Application No. 62/758,791, which was filed on 12 Nov. 2018, and
the entire disclosure of which is incorporated herein by
reference.
FIELD
[0002] The subject matter described herein relates to communication
networks.
BACKGROUND
[0003] The IEEE 802.1 Time-Sensitive Networking Task Group has
created a series of standards that describe how to implement
deterministic, scheduled Ethernet frame delivery within an Ethernet
network. Time-sensitive networking benefits from advances in time
precision and stability to create efficient, deterministic traffic
flows in an Ethernet network. Time-sensitive networks can be used
in safety critical environments, such as control systems for
automated industrial systems. In these environments, timely and
fast control of vehicles and/or machinery is needed to ensure that
operators and equipment at or near the vehicles and/or machinery
being controlled are not hurt or damaged.
[0004] Some known time-sensitive networks are scheduled in the time
domain utilizing frame sizes and traffic flow latencies as
scheduling constraints. But, limiting the acceptable range of frame
sizes and traffic flow latencies may add complexity and/or
unnecessarily constrain the potential solutions of the scheduling
device, especially when the time-sensitive network communicates
messages represented by frequency-based acoustic signals.
Furthermore, known time-sensitive networks are not scheduled based
on the quality or fidelity of signals transmitted through the
time-sensitive network, and therefore the signals exiting the
time-sensitive network may fail to satisfy quality standards.
BRIEF DESCRIPTION
[0005] In one or more embodiments, a communication system is
provided that includes multiple nodes of a time-sensitive network
and a scheduler device. The time-sensitive network optionally can
be disposed onboard one or more vehicles, but alternatively may not
be disposed onboard any vehicles. The nodes are communicatively
connected to each other via links. At least one of the nodes is
configured to obtain a first signal from a publishing device. The
first signal is represented in a frequency domain by multiple
frequency components. The scheduler device comprises one or more
processors and is configured to generate a schedule for
transmission of signals including the first signal within the
time-sensitive network. The schedule defines multiple slots
assigned to different discrete frequency sub-bands within a
frequency band. These slots have designated transmission intervals.
The nodes communicate (e.g., transmit) the first signal through the
time-sensitive network to a listening device such that the first
signal is received at the listening device within a designated time
window according to the schedule. At least some of the frequency
components of the first signal are transmitted through the
time-sensitive network within different slots of the schedule based
on the frequency sub-bands assigned to the slots.
[0006] In one or more embodiments, a method for communications is
provided that includes generating a schedule for transmission of
signals within a time-sensitive network. The schedule defines
multiple slots assigned to different discrete frequency sub-bands
within a frequency band. The slots have designated transmission
intervals. The method includes obtaining a first signal of the
signals from a publishing device. The first signal is represented
in a frequency domain by multiple frequency components. The method
also includes transmitting the first signal through the
time-sensitive network to a listening device such that the first
signal is received at the listening device within a designated time
window according to the schedule. At least some of the frequency
components of the first signal are transmitted through the
time-sensitive network within different slots of the schedule based
on the frequency sub-bands assigned to the slots.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] The present inventive subject matter will be better
understood from reading the following description of non-limiting
embodiments, with reference to the attached drawings, wherein
below:
[0008] FIG. 1 schematically illustrates one embodiment of a
communication system that includes a control system and a
time-sensitive network;
[0009] FIG. 2 is a graph plotting an acoustic signal in both a
frequency domain and a time domain according to an embodiment;
[0010] FIG. 3 is a graph illustrating a portion of a schedule for
the time-sensitive network according to an embodiment;
[0011] FIG. 4 depicts a portion of the schedule corresponding to a
single slot over time according to an embodiment;
[0012] FIG. 5 shows sine waves produced by two speakers according
to acoustic signals transmitted through the time-sensitive network
as the frequency components shown in FIG. 4; and
[0013] FIG. 6 illustrates a flowchart of one embodiment of a method
for communicating messages in a time-sensitive network.
DETAILED DESCRIPTION
[0014] One or more embodiments of the inventive subject matter
described herein relate to systems and methods that schedule the
transmission of signals in a time-sensitive network in the
frequency domain to improve the transmission of acoustic signals.
For example, the time-sensitive network is scheduled to transmit
acoustic signals that have a frequency content, such as but not
limited to audio compressed signals, ultrasound, vibrations,
acoustic phenomena, or the like. In one or more embodiments, a
control device of the time-sensitive network, such as a scheduler
device, is configured to account for signal fidelity of the signals
when scheduling the time-sensitive network. For example, the
scheduler may schedule the time-sensitive network based on one or
more signal fidelity targets, instead of (or in addition to) frame
size and traffic flow latency constraints. The signal fidelity
target may be a metric that indicates a general quality of the
signal that is output from the time-sensitive network. More
specifically, the signal fidelity target can represent a degree of
correspondence between a state or quality of a given signal exiting
the time-sensitive network and the state or quality of the same
signal entering the time-sensitive network.
[0015] At least one technical effect of the subject matter
described herein provides for reduced complexity in the scheduling
of time-sensitive networks by scheduling in the frequency domain
based on frequency components of acoustic signals instead of
scheduling in the time domain. Another technical effect of
scheduling in the frequency domain is improved signal fidelity
because the time-sensitive network functions as a low pass filter.
For example, by scheduling the transmission of signals along
different specific frequency sub-bands in a bandwidth, signal
components having frequencies outside of the scheduled frequency
sub-bands may be filtered out (e.g., not transmitted). The
frequencies that are filtered out may be attributable to background
noise, interference, minor components of the signals, and/or the
like. The filtering of signal components may reduce the complexity
and amount of information transmitted over the time-sensitive
network versus transmitting all components of the received signals,
which may improve the reliability and throughput of the network.
Another technical effect of scheduling in the frequency domain
based on the signal fidelity target, instead of frame size and/or
latency periods, is an increase in the number of potential
solutions that may be analyzed by the scheduler device when or
while generating the schedule. For example, by scheduling in the
frequency domain, it may be permissible for signals that are
communicated through the time-sensitive network to have periodic
latencies at nodes that would otherwise violate a latency
constraint.
[0016] FIG. 1 schematically illustrates one embodiment of a
communication system 100 that includes a control system 107 and a
time-sensitive network 109. The control system 107 controls
communications through the time-sensitive network 109. The
components shown in FIG. 1 represent hardware circuitry that
includes and/or is connected with one or more processors (e.g., one
or more microprocessors, field programmable gate arrays, and/or
integrated circuits) that operate to perform the functions
described herein. The components of the communication system 100
can be communicatively coupled with each other by one or more wired
and/or wireless connections. Not all connections between the
components of the communication system 100 are shown herein. The
time-sensitive network 109 can be configured to operate according
to one or more of the time-sensitive network standards of IEEE,
such as the IEEE 802.1ASTM-2011 Standard, the IEEE 802.1Q.TM.-2014
Standard, the IEEE 802.1Qbu.TM.-2016 Standard, and/or the IEEE
802.3br.TM.-2016 Standard.
[0017] The time-sensitive network 109 includes several node devices
105 (hereafter referred to as nodes) formed of network switches 104
and/or associated clocks 112 ("clock devices" in FIG. 1). While
only three nodes 105 are shown in FIG. 1, the communication system
100 can be formed of many more nodes 105 that may be distributed
over a large geographic area. The switches 104 of the nodes 105 may
include or represent electrical switches, routers, bridges, hubs,
and/or the like. The nodes 105 are communicatively connected to one
another via communication links 103 (referred to herein as links
103). The links 103 may include or represent physical communication
pathways, such as copper wires and/or cables, optical wires and/or
cables, Ethernet links, and the like. Optionally, the links 103 may
represent wireless communication pathways.
[0018] The time-sensitive network 109 can be an Ethernet network
that communicates data frames (or packets) as signals along traffic
flow paths 120 between communicating devices 106. A signal referred
to herein can be a message formed of many data packets or frames,
several data packets or frames making us less than an entire
message, or an individual data packet or frame. The traffic flow
paths 120 can be defined by the nodes 105 and the links 103 that
are in the different paths 120. For example, a data frame may be
transmitted through a path 120 from a first link 103 to a second
link 103 through a node 105 that connects the first and second
links 103, with the path 120 formed of the first and second links
103 and the node 105. The data frames can be sent along different
paths 120 according to a schedule of the time-sensitive network
109. The paths 120 may partially overlap or intersect each other.
For example, two paths 120 may partially overlap when the paths 120
share at least one of the same links 103. Two paths 120 may
intersect each other when the paths 120 share at least one of the
same nodes 105. The schedule restricts which data frames can be
communicated by each of the nodes 105 along one or more (or all)
paths 120 at different times.
[0019] Different data frames (e.g., signals) can be communicated at
different repeating scheduled time periods based on traffic
classifications of the frames. Some data frames represent messages
that are classified as time-critical traffic (referred to herein as
time-critical messages) while other data frames represent messages
classified as best-effort traffic (referred to herein as
best-effort messages). The time-critical messages have a higher
priority than the best effort messages. The time-critical messages
may be required to be communicated at or within designated periods
of time to ensure the safe operation of a powered system, such as
industrial machinery or a vehicle (e.g., locomotive, automobile,
off-road truck, marine vessel, aircraft, or the like). If a
time-critical message is not received within the designated time
period or window, the lack of timely receipt of the time-critical
message may risk harm to people and/or damage to the system or
surroundings. The best-effort messages include data frames that are
not required to ensure the safe operation of the powered system,
but that are communicated for other purposes (e.g., monitoring
operation of components of the powered system).
[0020] The communicating devices 106 that communicate via the
time-sensitive network 109 may be computers, sensors, servers,
control devices, or the like. In one embodiment, the devices 106
are disposed onboard one or more vehicles. For example, a first
vehicle device 106A of the devices 106 may be a different type of
device from a second vehicle device 106B and/or a third vehicle
device 106C. The device 106 that generates or inputs a message
(defined by one or more signals) into the time-sensitive network
109 for communication to another device 106 is referred to as a
publishing device (or publisher). The device 106 that receives the
message output from the time-sensitive network 109 is referred to
as a listening device (or listener). For example, a first vehicle
device 106A may be the publishing device and a second vehicle
device 106B may be the listening device for a given message
transmitted via the time-sensitive network 109. Optionally, one or
more of the devices 106 may be able to function as both publishing
devices and listening devices to enable bi-directional
communications between the devices 106 through the time-sensitive
network 109. Although three devices 106A-C are shown in FIG. 1, the
communication system 100 may enable more than three devices 106
(e.g., dozens, hundreds, or thousands), or only two devices 106, to
reliably communicate with one another.
[0021] The control system 107 includes a time-aware scheduler
device 102, a centralized network configurator device 108, and a
grandmaster clock device 110. The scheduler device 102 generates a
schedule that instructs each node 105 to transmit an Ethernet data
frame along a predefined path 120 at a prescheduled time, creating
deterministic traffic flows while sharing the same media with
legacy, best-effort Ethernet traffic. The time-sensitive network
109 has been developed to support hard, real-time applications
where delivery of frames of time-critical traffic must meet tight
schedules without causing failure, particularly in life-critical
vehicular and/or industrial control systems. The scheduler device
102 computes the schedule, and the schedule is installed at each
node 105 in the time-sensitive network 109 or some, but not all,
nodes 105. This schedule dictates when different types or
classification of signals are communicated by the switches 104 of
the nodes 105. For example, the schedule may dictate that a given
switch 104 transmits a time-critical message at a first time or
interval, and the switch 104 transmits a best effort message at a
different, second time or interval. The schedule may also dictate
arrival time windows or periods within which the data frames are
required to be received at a designated listening device, such as
the vehicle device 106B.
[0022] The scheduler device 102 may solve a system of scheduling
equations to create the schedule for the switches 104 of the nodes
105 to send Ethernet frames in a time-sensitive manner through the
communication system 100. This schedule may be subject to various
constraints, such as the topology of the time-sensitive network
109, the speed of communication by and/or between switches 104 in
the time-sensitive network 109, the amount of Ethernet frames to be
communicated through different switches 104, etc. This schedule can
be created to avoid two or more Ethernet frames colliding with each
other at a switch 104 (e.g., to prevent multiple frames from being
communicated through the same switch 104 at the same time).
[0023] The scheduler device 102 may be formed from hardware
circuitry that is connected with and/or includes one or more
processors that generate the schedule for the time-sensitive
network 109. The scheduler device 102 is synchronized with the
grandmaster clock device 110 of the control system 107. The
grandmaster clock device 110 includes a clock to which the clocks
112 of the nodes 105 are synchronized.
[0024] The centralized network configurator device 108 (referred to
herein as configurator device 108) of the control system 107 is
comprised of software and/or hardware that has knowledge of the
physical topology of the time-sensitive network 109 as well as the
traffic flow paths 120. The configurator device 108 can be formed
from hardware circuitry that is connected with and/or includes one
or more processors that determine or otherwise obtain the topology
information from the nodes 105 and/or user input.
[0025] The physical topology of the time-sensitive network 109 maps
the hardware of the time-sensitive network 109, including the
locations (e.g., absolute and/or relative locations) of all of the
nodes 105, the vehicle devices 106, and the links 103 that connect
the nodes 105 and the vehicle devices 106. The topology can also
identify which of the nodes 105 are directly coupled with other
nodes 105 and/or the vehicle devices 106 via links 103. The
locations of the hardware components can be used to determine
distances between the hardware components, which may be utilized by
the scheduler device 102 when scheduling flow paths 120 for
conveying data frames within designated time windows. The physical
topology may also include additional information about the hardware
within the time-sensitive network 109, such as the types of
hardware (e.g., part numbers), instructions for communicating with
the various nodes 105 and other hardware, and/or the like.
[0026] The topology information may be stored in a database and
accessed by the configurator device 108. Alternatively, the
configurator device 108 may generate the topology information by
communicating with the nodes 105 in the time-sensitive network 109
to determine the types and locations (relative or absolute) of the
nodes 105. The configurator device 108 can provide this topology
information to the scheduler device 102, which uses the topology
information to determine the schedules for communication of
messages between the vehicle devices 106. The configurator device
108 and/or scheduler device 102 can communicate the schedule to the
different nodes 105.
[0027] The hardware circuitry and/or processors of the configurator
device 108 can be at least partially shared with the hardware
circuitry and/or processors of the scheduler device 102. For
example, one or more processors and associated circuitry may be
configured to perform the operations of both the configurator
device 108 and the scheduler device 102 as described herein.
Alternatively, the one or more processors of the configurator
device 108 are all discrete and separate from the one or more
processors of the scheduler device 102. In yet another embodiment,
a subset of processors of the configurator device 108 is shared in
common with the scheduler device 102, and/or a subset of processors
of the scheduler device 102 is shared in common with the
configurator device 108.
[0028] The control system 107 (e.g., the scheduler device 102) may
communicate with the time-aware nodes 105 (e.g., the switches 104
with respective clocks 112) through a network management protocol.
For example, a link layer discovery protocol can be used to
exchange information between the nodes 105 and the scheduler device
102. The time-aware nodes 105 may implement a control plane element
that forwards the commands from the scheduler device 102 to their
respective hardware. The configurator device 108 may poll the nodes
105 and the vehicle devices 106 to retrieve topology information of
the time-sensitive network 109 via the network management protocol,
and the topology information may be provided to the scheduler
device 102.
[0029] In one or more embodiments, the communication system 100 is
disposed on one or more vehicles of a vehicle system.
Alternatively, the communication system 100 may not be disposed
onboard any vehicle. In FIG. 1, the communication system 100 is
disposed on a locomotive 150 (e.g., a propulsion-generating rail
vehicle) of a rail vehicle system. The locomotive 150 may be
mechanically and communicatively coupled to another locomotive or a
non-propulsion generating rail car. For example, the locomotive 150
may be communicatively coupled to another locomotive by a wired
connection, such as a 27-pin trainline cable. The components of the
communication system 100, such as the nodes 105, the configurator
device 108, the scheduler device 102, and the vehicle devices 106,
may be entirely disposed onboard the locomotive or the rail vehicle
system, such that all components are disposed onboard the same
vehicle or onboard multiple vehicles that travel together along
routes as a vehicle system. Alternatively, at least some of the
components of the communication system 100, such as the
configurator device 108 and/or the scheduler device 102, may be
disposed off-board the rail vehicle system.
[0030] While the communication system 100 is shown as being
disposed onboard a locomotive 150 of a rail vehicle system,
alternatively, the communication system 100 may be disposed onboard
another type of vehicle such as an automobile, a marine vessel, a
mining vehicle, or another off-highway vehicle (e.g., a vehicle
that is not legally permitted or that is not designed for travel
along public roadways). In yet another embodiment, the
communication system 100 may be installed off-board a vehicle, such
as installed in an industrial setting (e.g., factory, manufacturing
plant, or the like). For example, the communication system 100
optionally may be used to provide network communications in systems
other than vehicle networks.
[0031] The vehicle devices 106 may provide data and/or control
signals that are important for the safe operation of the rail
vehicle system. The vehicle devices 106 may represent one or more
of traction motor controllers, an engine control unit, an auxiliary
load controller, an input/output device, sensors, and/or the like.
The time-sensitive network 109 is utilized to ensure precise,
uninterrupted communication between these devices to ensure safe
operation of the locomotive 150. For example, the communications
between these devices that are used for controlling the movement of
the locomotive 150 may be designated as time-critical messages that
have a greater priority than best effort messages between
different, less critical vehicle devices.
[0032] In FIG. 1, the first vehicle device 106A may be an
input/output device. The input/output device 106A may represent one
or more devices that receive input from an operator onboard the
locomotive 150 and/or that present information to the operator. The
input/output device 106A can represent one or more touchscreens,
keyboards, styluses, display screens, lights, speakers, or the
like.
[0033] The second vehicle device 106B may be a traction motor
controller that controls operation of traction motors 152 of the
locomotive 150. The traction motor controller 106B represents
hardware circuitry that includes and/or is connected with one or
more processors (for example, one or more microprocessors, field
programmable gate arrays, and/or integrated circuits) that generate
control signals for controlling the traction motors 152. For
example, based on or responsive to a throttle setting selected by
an operator input via the input/output device 106A and communicated
to the traction motor controller 106B via the time-sensitive
network 109, the traction motor controller 106B may change a speed
at which one or more of the traction motors 152 operate to
implement the selected throttle setting.
[0034] The third vehicle device 106C may be an engine control unit,
an auxiliary load controller, a sensor, or the like. For example,
each of the engine control unit and the auxiliary load controller
represents hardware circuitry that includes and/or is connected
with one or more processors (for example, one or more
microprocessors, field programmable gate arrays, and/or integrated
circuits) that generate control signals. The control signals
generated by the engine control unit are communicated to an engine
of the locomotive 150 (for example, based on input provided by the
input/output device 106A) in order to control operation of the
engine of the locomotive 150. The control signals generated by the
auxiliary load controller are communicated to one or more auxiliary
loads of the locomotive 150 to control operation of the one or more
auxiliary loads. The auxiliary loads may consume electric current
without propelling movement of the locomotive 150. The auxiliary
loads can include, for example, fans or blowers, battery chargers,
lights, and/or the like. The third vehicle device 106C is referred
to as the engine control unit 106C herein.
[0035] To ensure that communications between the vehicle devices
106 (e.g., input/output devices, traction motor controllers, engine
control units, auxiliary load controllers, sensors, and/or the
like) are sent and/or received in time, the scheduler device 102
schedules the communications through the time-sensitive network
109. Communicating through the time-sensitive network 109 ensures,
for example, that a change to a throttle setting received by the
input/output device is received by the traction motor controllers
within a designated period of time, such as within a few
milliseconds. In contrast to a conventional Ethernet network
(operating without a time-sensitive network) that communicates data
frames or packets in a random manner, the time-sensitive network
109 communicates the data frames or packets according to the type
or category of the data or information being communicated to ensure
that the data is communicated within designated time periods or at
designated times. With respect to some vehicle control systems, the
late arrival of data can have significantly negative consequences,
such as an inability to slow or stop movement of a vehicle in time
to avoid a collision.
[0036] As described above, the time-sensitive network 109 may be an
Ethernet network that prioritizes communications and dictates when
certain communications occur to ensure that certain data frames or
packets are communicated within designated time periods or at
designated times. The communications between or among some of the
vehicle devices 106 may include time sensitive information or data.
For example, data indicative of a change in a brake setting may
need to be communicated from the input/output device 106A to the
traction motor controller 106B within several milliseconds of being
sent by the input/output device 106A into the network 109. The
failure to complete this communication within the designated time
limit or period of time may prevent the rail vehicle system from
braking in time. Non-time sensitive communications may be
communications that do not necessarily need to be communicated
within a designated period of time, such as communication of a
location of the vehicle system from a global positioning system
(GPS) receiver, a measurement of the amount of fuel from a fuel
sensor, etc. These non-time sensitive communications may be
designated as best effort communications that are a lower priority
than the time sensitive communications.
[0037] Best effort communications may be communicated within the
time-sensitive network 109 when there is sufficient bandwidth in
the network 109 to allow for the communications to be successfully
completed without decreasing the available bandwidth in the network
109 below a bandwidth threshold needed for the communication of
time sensitive communications between publishing devices and
listening devices. For example, if 70% of the available bandwidth
in the network 109 is needed at a particular time to ensure that
communications with the engine control unit 106C and traction motor
controller 106B successfully occur, then the remaining 30% of the
available bandwidth in the network 109 may be used for other
communications, such as best effort communications with the
auxiliary load controller. The bandwidth threshold may be a
user-selected or default amount of bandwidth. The communication of
best effort communications may be delayed to ensure that the time
sensitive communications are not delayed.
[0038] The priority statuses of different types of communications
may be set by the control system 107 and/or the operator of the
locomotive 150. For example, the control system 107 may designate
that all communications to and/or from the engine control unit
106C, the traction motor controller 106B, the input/output device
106A, and sensors that monitor engine conditions, traction motor
conditions, and brake conditions are time sensitive communications,
and communications to and/or from onboard display devices, the
auxiliary load controller, and auxiliary devices are best effort
communications. Optionally, the type of information being
communicated by these devices may determine the type of
communications. For example, the control system 107 may establish
that control signals (e.g., signals that change operation of a
device, such as by increasing or decreasing a throttle of a
vehicle, applying brakes of a vehicle, etc.) communicated to the
engine control unit 106C and/or traction motor controller 106B may
be time sensitive communications while status signals (e.g.,
signals that indicate a current state of a device, such as a
location of the locomotive 150) communicated from the engine
control unit 106C and/or traction motor controller 106B are best
effort communications.
[0039] According to one or more embodiments described herein, the
time-sensitive network 109 is configured to communicate acoustic
signals between the vehicle devices 106 in addition to, or as an
alternative to, conventional electrical signals. The acoustic
signals may each be represented by multiple frequency components,
such as components at different frequencies within a frequency band
or spectrum. The acoustic signals may include audio signals,
audible sound signals, ultrasound signals, infrasound or low
frequency signals, vibrations, and/or the like. An audio signal may
represent a signal in an audio and/or video application. Audible
sounds are in the frequency range perceptible to an ordinary
person. The frequencies of the ultrasound signals and the
infrasound signals are greater and less than, respectively,
frequencies perceptible to the ordinary person. The vibration
signals may refer to the vibrations of various components onboard
the locomotive 150, such as the engine.
[0040] FIG. 2 is a graph 200 plotting an acoustic signal 202 in
both a frequency domain and a time domain according to an
embodiment. The graph 200 has a frequency axis 204, a time axis
206, and an amplitude axis 208. The acoustic signal 202 can be
represented in the time domain as a single waveform 210 that has
multiple different amplitude peaks and multiple different amplitude
valleys over time. The acoustic signal 202 can also be represented
in the frequency domain as multiple frequency components 212. The
acoustic signal 202 in the frequency domain shows how much of the
signal 202 lies within different frequency bands. The frequency
components 212 have different frequencies, and therefore are spaced
apart along the frequency axis 204 within different frequency
bands. The acoustic signal 202 has three frequency components 212
in the illustrated embodiment, but other acoustic signals may have
only two or at least four frequency components. When viewed in the
time domain, each of the frequency components 212 is a sine wave
214 with a corresponding amplitude and period (e.g., frequency). In
the frequency domain, the frequency components 212 can be
represented by bars 218. For example, at a specific time 216, the
three frequency components 212 have different frequencies (as
represented by spaced apart locations of bars 218 along the
frequency axis 204) and different amplitudes (as represented by the
different heights of the bars 218).
[0041] The acoustic signal 202 is a combination of the frequency
components 212. Each of the frequency components 212 may be defined
by a frequency, an amplitude, and/or a phase (e.g., phase shift).
Different frequency components 212 may have different frequencies,
amplitudes, and/or phases. The frequency components 212 may be
represented as complex numbers including an amplitude (e.g.,
magnitude) of the component 212 and relative phase of the wave
(e.g., angle) at a given frequency.
[0042] On the locomotive 150, the acoustic signal 202 or other
acoustic signals may represent a signature vibration of the engine
that is monitored and/or measured by a sensor. The acoustic signal
202 or other acoustic signals may represent a phase and/or
frequency of electrical current conveyed to or from the traction
motors 152 (shown in FIG. 1). The acoustic signal 202 or other
acoustic signals may represent a voice command input by an operator
utilizing a microphone of the input/output device 106A (shown in
FIG. 1). The acoustic signal 202 or other acoustic signals may
represent audio and/or video content captured by a sensor and/or
camera onboard the locomotive 150.
[0043] FIG. 3 is a graph 300 illustrating a portion of a schedule
306 for the time-sensitive network 109 according to an embodiment.
The graph 300 has a vertical axis 302 that represents a frequency
band 308 or spectrum. The graph 300 also has a horizontal axis 304
representing time. The schedule 306 may be generated by the
scheduler device 102 (shown in FIG. 1). In an embodiment, the
scheduler device 102 generates the schedule 306 in the frequency
domain. The schedule 306 dictates that different frequency
components 212 of one or more signals (e.g., the signal 202 shown
in FIG. 2) are transmitted through the time-sensitive network 109
at different time intervals. FIG. 3 shows five frequency components
212, identified as FC.sub.1, FC.sub.2, FC.sub.3, FC.sub.4, and
FC.sub.5. All five frequency components 212 optionally may be
components of the same acoustic signal. Alternatively, the five
frequency components 212 may represent at least two different
acoustic signals.
[0044] In an embodiment, the schedule 306 defines multiple slots
310 that are assigned to different frequency sub-bands within the
frequency band 308. The frequency sub-bands are discrete from each
other, such that the slots 310 do not have overlapping sub-bands.
The schedule 306 defines five slots 310 in FIG. 3, which are
identified as 310A, 310B, 310C, 310D, 310E, but the schedule 306
may have any number of slots 310. For example, the slot 310B is
assigned to a frequency sub-band between frequencies ii and iii in
FIG. 3, which is a frequency range. In a non-limiting example, the
frequency ii may represent 50 Hz and the frequency iii represents
100 Hz, such that the slot 310B is assigned to the frequency
sub-band from 50 Hz to 100 Hz. The scheduler device 102 may assign
the frequency sub-bands to the different slots 310 during the
scheduling process. Optionally, at least some of the frequency
sub-bands assigned to the slots 310 may have different widths
(e.g., different sizes or ranges between the corresponding two
outer frequencies). For example, the slots 310C and 310E are
assigned to respective sub-bands that have greater widths than the
respective sub-bands assigned to slots 310A, 310B, and 310D.
Alternatively, all of the slots 310 may be assigned to frequency
sub-bands having the same widths although spaced apart along the
frequency band 308.
[0045] The schedule 306 designates that the different slots 310
have different transmission intervals 314. The transmission
intervals 314 represent designated times or time windows at which a
particular signal or data frame is transmitted by the nodes 105
(shown in FIG. 1) of the time-sensitive network 109. For example,
in the schedule 306 shown in FIG. 3, the slot 310A has a
transmission interval 314 between times t.sub.3 and t.sub.4.
Therefore, a node 105 may gate (e.g., not transmit) a signal or
data frame that is within the slot 310A until after time t.sub.3,
at which the node 105 transmits the signal or data frame to a
subsequent node 105 or to a listening device along the path 120
according to the schedule. The node 105 also gates similar signals
within the slot 310A after time t.sub.4 until the transmission
cycle repeats. The slot 310B has a first transmission interval 314
between times 0 and t.sub.1 and a second transmission interval 314
between times t.sub.5 and t.sub.6. Optionally, the transmission
intervals 314 may be cyclical. For example, the entire transmission
period from time 0 to t.sub.5 may repeat such that the transmission
interval 314 between times t.sub.5 and t.sub.6 may be a repeat of
the interval 314 between times 0 and t.sub.1. The transmission
intervals 314 according to the schedule may have the same
durations, or at least some of the transmission intervals 314 may
have longer durations than other transmission intervals 314.
[0046] In at least one embodiment, at least some of the frequency
components 212 of the signal 202 (shown in FIG. 2) are transmitted
through the time-sensitive network 109 (shown in FIG. 1) within
different slots 310 of the schedule 306 based on the frequency
sub-bands assigned to the slots 310. The frequency components 212
may be transmitted within slots 310 that are assigned to sub-bands
that correspond to the frequencies of the frequency components 212.
For example, a frequency component 212 of the signal 202 that has a
frequency of 207 Hz may be transmitted within a slot 310 assigned
to a frequency sub-band that contains 207 Hz, such as a sub-band
from 200 Hz to 250 Hz. In FIG. 3, a first frequency component 212
("FC.sub.1") is transmitted within the slot 310B, such that the
first frequency component 212 has a transmission interval 314
between times 0 and t.sub.1. A second frequency component 212
("FC.sub.2") of the same signal 202 has a greater frequency than
the first frequency component and is transmitted within the slot
310E. For example, the frequency of the second frequency component
212 may be 991 Hz, which is contained within the frequency sub-band
310E. A third frequency component 212 ("FC.sub.3") of the same
signal 202 has a frequency between the first and second components,
and is transmitted within the slot 310D.
[0047] The schedule 306 may stagger the transmission intervals 314
of different frequency components 212 such that one frequency
component 212 of a signal may be transmitted by the nodes 105 at
different times than the nodes 105 transmit another frequency
component 212 of the same signal or a different signal. As shown in
FIG. 3, the three frequency components 212 (FC.sub.1 through
FC.sub.3) of the same signal 202 are transmitted at different
transmission intervals 314. Therefore, these three frequency
components 212 may arrive at the designated listening vehicle
device 106 at slightly different (e.g., staggered) times. According
to at least one embodiment, the different transmission intervals
314 have relatively short durations, such as on the order of
microseconds. Due to the short durations, the staggered frequency
components 212 are able to be merged and processed at the listening
device without a person being able to perceive any offset. For
example, if the listening device is a speaker of the input/output
device 106A (shown in FIG. 1), the staggered frequency components
212 of the signal 202 can be reconstructed and output by the
speaker without a person being able to comprehend any noise or
signal degradation caused by a delay between the frequency
components 212. The nature of the time-sensitive network 109
ensures that the various frequency components 212 of the signal 202
are received on time within a designated time window according to
the schedule. The use of the time-sensitive network 109 to transmit
frequency-based signals (such as vibration signals, audio signals,
ultrasound signals, and the like) according to a precise schedule
may make buffering at the listening device 106 unnecessary.
[0048] Optionally, the scheduler device 102 may schedule the
time-sensitive network 109 in the frequency domain such that the
time-sensitive network 109 functions as a low pass filter. The
filter may be used to filter out (e.g., not transmit) certain
frequency components of the signals. For example, certain
frequencies of the signals may be attributable to background noise,
interference, cross-talk, or the like. The signals may also contain
frequencies that are unnecessary, such as frequency components of
audio signals that are outside of the audible frequency range that
can be heard by ordinary persons or frequency components that are
masked by other frequencies and are therefore unintelligible. The
time-sensitive network 109 can be used to filter out such frequency
components that are associated with background, interference, or
unnecessary frequencies from the frequency components of the
signals that are transmitted through the network 109. This
filtering reduces the amount of data transmitted through the
time-sensitive network 109, improving the throughput thereof.
[0049] For example, the scheduler device 102 may utilize the
time-sensitive network 109 as a filter by assigning the frequency
sub-bands to the slots 310 such that the assigned sub-bands
represent less than an entirety of the frequency band 308. For
example, as shown in FIG. 3, the sub-bands between frequencies i
and ii, between frequencies v and vi, and between frequencies ix
and x are unassigned to the slots 310. Frequency components of the
signals that have frequencies contained within the unassigned
sub-bands may not be transmitted through the network 109 to the
listening device 106. These frequency components are filtered
out.
[0050] The scheduler device 102 may assign the frequency sub-bands
to the slots 310 based on an analysis of one or more signals that
would be transmitted through the time-sensitive network 109. For
example, the scheduler device 102 may analyze a dynamic range of
one or more signals to identify various frequency components of the
signals. Based on the analysis, the scheduler device 102 may select
certain frequencies that are unnecessary to represent the one or
more signals, such as frequencies determined to be attributable to
noise or interference and frequencies that are masked or outside of
a perceptible range. After selecting the frequencies that are
unnecessary to represent the one or more signals, the schedule
device 102 generates the schedule 306 such that these frequencies
are not assigned to the slots 310.
[0051] In an embodiment, the frequency components 212 transmitted
through the time-sensitive network 109 may be encoded within
Ethernet data frames. For example, the frequency components 212 may
be digitally encoded within frames. The Ethernet frames include
data that may represent the frequency, amplitude, and/or phase of
each frequency component 212 encoded therein. Optionally, the six
boxes representing frequency components 212 shown in FIG. 3 may be
six different Ethernet data frames transmitted through the network
109. Each data frame may include a single frequency component 212.
Alternatively, at least some data frames may encode multiple
frequency components 212 in a single frame.
[0052] In one or more embodiments, the scheduler device 102
generates the schedule 306 based on a signal fidelity target. The
signal fidelity target may be a metric that indicates a general
quality of the signal that is output from the time-sensitive
network 109. For example, the signal fidelity target may represent
a degree of correspondence between a state or quality of a given
signal exiting the time-sensitive network 109 and the state or
quality of the same signal entering the time-sensitive network 109.
The signal fidelity may be determined by comparing the signal at
the state provided by the publishing device 106 to the same signal
at the state provided by the network 109 to the listening device
106. Filtering out certain frequencies of the signal to improve the
throughput of the time-sensitive network 109 may negatively affect
the signal fidelity because the outgoing signal differs from the
incoming signal by at least the filtered out components. Therefore,
there may be a tradeoff associated with filtering out components of
the signals. Reduced filtering may improve the signal fidelity of
the transmitted signals as the cost of reducing network throughput
and increasing the load on the network 109.
[0053] The scheduler device 102 may obtain a designated signal
fidelity target. The signal fidelity target may be stored in a
memory and accessed by the scheduler device 102. For example, the
signal fidelity target may be based on a standard or regulation.
Alternatively, the signal fidelity target may be selected by an
operator using the input/output device 106A (shown in FIG. 1), and
the operator selection may be received by the scheduler device 102.
Upon obtaining the signal fidelity target, the scheduler device 102
utilizes the signal fidelity target as a constraint and schedules
the time-sensitive network 109 to satisfy the signal fidelity
target. The scheduler device 102 may base the assignment of the
frequency sub-bands to the slots 310 on the signal fidelity target.
For example, the scheduler device 102 may assign the slots 310 to a
sufficient number and size of frequency sub-bands in the frequency
band 308 to satisfy the signal fidelity target. Increasing the
number and/or size of sub-bands assigned to the slots 310 may
reduce the number of frequency components of the signals that are
filtered out by the time-sensitive network 109, thereby increasing
the signal fidelity. In an embodiment, the scheduler device 102
assigns the frequency sub-bands to the slots 310 such that the
signal fidelity achieved by the network 109 is at or only slightly
greater than the designated signal fidelity target. For example, if
it is determined that a potential schedule does not satisfy the
signal fidelity target, then the potential schedule is modified
and/or another potential is generated to increase the signal
fidelity of the network 109. The schedule may be modified to
increase the signal fidelity by increasing the number of sub-bands
assigned to the slots 310 and/or the widths (e.g., sizes) of the
sub-bands assigned to the slots 310. As a result, the network 109
is scheduled to satisfy the designated signal fidelity target, but
the network 109 can still act as a low pass filter to filter out
some unnecessary frequency components.
[0054] In an embodiment, the scheduler device 102 generates the
schedule based on the designated signal fidelity target, which is a
frequency-based constraint, without utilizing time-based
constraints such as a frame size limit and/or a periodic latency
limit. For example, typical Ethernet networks may be scheduled
according to various constraints, such as the topology, requested
flow latency, frame sizes, and/or the like. But, the scheduler
device 102 optionally may not utilize frame size or latency as
constraints when generating the schedule 306 for the
frequency-based communication of signals through the time-sensitive
network 109. By not limiting the frame sizes and/or latency, the
scheduler device 102 may be able to generate a schedule 306 in
satisfaction of the designated signal fidelity target that would
not have been possible if the frame size, periodic latency, and/or
other constraints were applied. For example, the schedule 306 that
is generated may have one or more frame sizes that would be outside
of the permissible frame size limit if the frame size constraint
was applied.
[0055] In an embodiment, the time-sensitive network 109 is
configured to combine the various frequency components 212 of a
given signal after the frequency components 212 are transmitted
through the network 109. For example, a node 105 of the
time-sensitive network 109 that is communicatively coupled to the
designated listening device 106 may combine the frequency
components 212 to form an intact (e.g., reconstructed) signal 202.
The node 105 then transmits the intact signal 202 to the listening
device 106 for the listening device 106 to process the signal. For
example, combining the frequency components 212 to reconstruct the
intact signal 202 may convert the frequency-based representation of
the signal to a time-based representation of the signal 202.
Optionally, a Fourier transform or the like may be applied to
convert the signal 202. In an alternative embodiment, the listening
device 106, not the node 105 communicatively coupled to the
listening device 106, is configured to combine the frequency
components 212 to reconstruct the signal 202.
[0056] In one or more embodiments, the scheduler device 102 may
dynamically update the schedule 306 during the operation of the
time-sensitive network 109. For example, after some signals are
transmitted through the time-sensitive network 109, the scheduler
device 102 may monitor the fidelity of the signals and other
parameters. The scheduler device 102 may be configured to modify or
update the schedule 306 based on the monitored parameters in order
to improve the signal fidelity or the like. The scheduler device
102 modifies the schedule 306 by adjusting a width (e.g., size) of
the frequency sub-band assigned to one or more of the slots 310,
assigning additional frequency sub-bands to slots 310, assigning
fewer frequency sub-bands to slots 310, altering the transmission
intervals 314 of the slots 310, altering the order in which the
frequency components 212 are transmitted, adjusting the traffic
flow paths 120 through the network 109, and/or the like. For
example, if the monitored signal fidelity drops below the
designated signal fidelity target, the scheduler device 102 may
increase the width (e.g., size) of at least one of the assigned
frequency sub-bands which may reduce the portion of the signals
that are filtered out, improving the signal fidelity.
[0057] The signals received by the listening devices 106 onboard
the locomotive 150 (shown in FIG. 1) may be used to control the
movement of the rail vehicle system. For example, the signal 202
(shown in FIG. 2) may represent a measurement of a component
onboard the locomotive 150, such as the engine, traction motors
152, or an auxiliary load. Alternatively, the signal may be
represent a command received from an operator using the
input/output device 106A or a command received from another device
located on another vehicle system or at a dispatch center. The
signal 202 optionally may be classified as a time-critical message,
or alternatively as a best effort message. Responsive to receiving
the signal 202, the locomotive 150 may be controlled to slow or
stop movement. For example, the brakes of the locomotive 150 may be
automatically applied upon receipt of the signal 202 at the
listening device.
[0058] FIG. 4 depicts a portion of the schedule 306 corresponding
to a single slot 310 over time according to an embodiment. In the
illustrated embodiment, the slots 310 may be assigned to narrow
frequency sub-bands and/or individual frequencies. In a
non-limiting example, the illustrated slot 310 may be assigned to
the frequency 100 Hz, or may be assigned to a narrow sub-band that
includes 100 Hz, such as from 99 Hz to 101 Hz. In the illustrated
embodiment, the frequency components 212 of an acoustic signal that
is transmitted through the time-sensitive network 109 are assigned
to various slots 310 based on the frequencies, but the frequency
information is not transmitted with the frequency components 212.
For example, the frequency components 212 shown in FIG. 4 contain
information about the destination device and the amplitude.
[0059] Optionally, the frequency that is associated with the slot
310 may be selected based on a common or notable frequency within
the acoustic signals that are conveyed through the network 109. For
example, if a frequency component has a frequency of 99 Hz, then
the slot 310 may be assigned to 99 Hz such that all frequency
components 212 transmitted along the slot 310 have the 99 Hz
frequency. Alternatively, if the slot 310 is associated with 100 Hz
and an incoming frequency component of an input acoustic signal has
a frequency that is 99 Hz, then the system may slightly degrade the
quality of the signal by scheduling that frequency component for
transmission within the 100 Hz slot. Such a frequency component
will be interpreted by the listening device as having the modified
frequency of 100 Hz, but the small discrepancy may be undetectable
and therefore within a permissible error range.
[0060] In the illustrated embodiment, the acoustic signals are
transmitted through the time-sensitive network 109 to a pair of
receiving speakers that play (e.g., emit) the acoustic signals. The
destination device for each frequency component 212 is one of the
two speakers, either speaker A or speaker B. The frequency
components 212 are scheduled to transmit at 10 ms transmission
intervals 314 in FIG. 4, but different intervals may be used in
other embodiments. The first frequency component 212A that is
transmitted at time 0 in the slot 310 shows "B=1", which indicates
that the destination device is speaker B, and the amplitude of the
given frequency is 1. The second frequency component 212B that is
transmitted at the second interval 314 starting at time 10 ms shows
"A=0.5", which indicates that the destination device is speaker A,
and the amplitude of the given frequency is 0.5.
[0061] Additional reference is made to FIG. 5, which shows sine
waves 360 produced by the speaker A 362 and by the speaker B 364
according to the acoustic signals transmitted through the
time-sensitive network 109 as the frequency components 212 shown in
FIG. 4. For example, upon receipt of the first frequency component
212A, speaker B is configured to implement the signal by emitting a
tone having the frequency associated with the slot 310 shown in
FIG. 4 and the amplitude of 1. If the associated frequency is 100
Hz, speaker B plays a tone with a 100 Hz frequency and a 1
amplitude. The amplitude values may be based on a reference
amplitude or may have a unit such as decibels. Speaker A does not
emit a tone during the first transmission interval 314 until time
10 ms because the first frequency component 212A was addressed only
to speaker B. During the second transmission interval 314 that
starts at time 10 ms, speaker A receives the second frequency
component 212B and emits a tone having the designated frequency and
the commanded amplitude of 0.5. Speaker B continues to play the
tone having the amplitude of 1 until an additional command for
speaker B is received. Therefore, during the second transmission
interval, the sine waves 360 of speakers A and B have the same
frequency, but the sine wave 360 of speaker B has a greater
amplitude than the sine wave 360 of speaker A.
[0062] At 20 ms, the amplitude of the tone produced by speaker A
increases to 1.5 due to the receipt of a third frequency component
212C shown in FIG. 4. No frequency component 212 is transmitted in
the interval 314 starting at 30 ms, so the speakers A and B
continue to emit the same respective tones during this interval 314
as the previous interval 314 starting at 20 ms. At 40 ms, the
frequency component 212 indicates that speaker B has an amplitude
of 0, which explicitly stops speaker B from producing a tone at the
designated frequency. Speaker A is also explicitly stopped from
producing the designated frequency at time 50 ms. Therefore, after
time 50 ms, neither speaker generates a tone having the designated
frequency associated with the slot 310.
[0063] FIGS. 4 and 5 illustrate a single slot 310, but it is
understood that the schedule 306 for the time-sensitive network 109
may schedule the transmission of frequency components 212 of
acoustic signals as shown in FIGS. 4 and 5 for each of the slots
310 of the frequency band 308 (shown in FIG. 3) to convey acoustic
signals along different frequencies. For example, if the slot 310
shown in FIG. 4 is associated with the frequency 100 Hz, then
additional slots 310 associated with other frequencies such as 50
Hz, 25 Hz, 12.5 Hz, and/or the like may be similarly scheduled to
enable the speakers A and B to produce sounds (e.g., music) having
multiple frequencies. The audio speaker device (e.g., receiver)
that receives the acoustic signals from the network 109 may be
buffer-less because the speakers can simply play the amplitudes of
the designated frequencies as the frequency components are received
at the speaker device.
[0064] FIG. 6 illustrates a flowchart of one embodiment of a method
400 for communicating messages in a time-sensitive network onboard
a vehicle system. The method 400 can represent operations performed
by the control system 107 (e.g., by the scheduler device 102) of
the communication system 100. Referring to FIGS. 1 through 5, at
402, a signal fidelity target is obtained. The signal fidelity
target may be received by an operator selection or accessed in a
memory. The signal fidelity target may represent a degree of
correspondence between a state of a signal exiting a time-sensitive
network 109 at a listening device 106 and a state of the same
signal entering the time-sensitive network 109 at a publishing
device 106.
[0065] At 404, a schedule 306 is generated for transmission of
signals within the time-sensitive network 109 onboard one or more
locomotives 150. The schedule 306 defines multiple slots 310
assigned to different discrete frequency sub-bands within a
frequency band 308. The slots 310 have designated transmission
intervals 314. The schedule 306 may be generated in the frequency
domain. For example, signals are transmitted through the network
109 based on frequency components 212 of the signals. The schedule
306 is generated to satisfy the signal fidelity target. For
example, the slots 310 may be assigned to a sufficient number of
frequency sub-bands to satisfy the signal fidelity target.
Optionally, the schedule 306 may be generated without utilizing one
or more time-based parameters, such as frame size and/or periodic
latency, as constraints. The schedule 306 may be generated such
that the time-sensitive network 109 functions as a low pass filter.
For example, the frequency sub-bands assigned to the slots 310 may
represent less than an entirety of the frequency band 308, and the
time-sensitive network 109 may not transmit frequency components
212 of signals that have frequencies outside of the assigned
sub-bands.
[0066] At 406, a signal 202 is obtained from a publishing device
106. The signal 202 is represented in the frequency domain by
multiple frequency components 212. The signal 202 may be one or
more of an audio signal, an ultrasound signal, a vibration signal,
an audible sound signal, an infrasound signal, or the like. The
signal 202 may represent a measurement of a component onboard the
locomotive 150. The frequency components 212 of the signal 202 may
be encoded within Ethernet frames.
[0067] At 408, the frequency components 212 of the signal 202 are
transmitted through the time-sensitive network 109 to a listening
device 106 according to the schedule 306. The time-sensitive
network 109 includes various nodes 105 and communication links 103
between the nodes 105. At least some of the frequency components
212 of the signal 202 are transmitted within different slots 310 of
the schedule 306 based on the frequency sub-bands assigned to the
slots 310. For example, a first frequency component 212 of the
signal 202 may be transmitted within a first slot 310A of the
schedule 306 assigned to a frequency sub-band that contains a
frequency of the first frequency component 212. A second frequency
component 212 of the signal 202 may be transmitted within a second
slot 310B of the schedule 306 assigned to a different frequency
sub-band that contains a frequency of the second frequency
component 212. After transmission through the network 109, the
different frequency components 212 may be combined to form an
intact signal 202 that is provided to the listening device 106. The
combination may include converting the signal 202 from a
frequency-based representation to a time-based representation. The
signal 202 received at the listening device 106 may be used for
controlling operations (e.g., movement) of the vehicle system.
[0068] In one or more embodiments, a vehicle-based communication
system is provided that transports frequency sub-band encoded
signals through a time-sensitive network. The signals have a
frequency content that may include one or more of audio compressed
signals, ultrasounds, vibrations, acoustic phenomena (e.g.,
acousto-optics), and/or the like. The use of time-aware scheduler
devices on a time-sensitive network may allow for reducing or
omitting various signal compression and/or conversion steps, such
as packing and unpacking compressed signals.
[0069] In a non-limiting example, a scheduler device can divide a
time-sensitive network into a designated number of slots (e.g., 32
slots) that are each assigned to a specific frequency sub-band. A
slot may be sent at a designated transmission interval, such as
once every 156 microseconds. The size of the slots can be adjusted
to reflect the number of streams to be sent over the network. The
size of the slots may be calibrated. In a non-limiting example, 32
slots may be designated that each have a size of 2000 octets. For a
1 Gbps port, the corresponding frequency band occupies 16
microseconds. The total bandwidth consumed by the 32 slots is 512
microsecond. Assuming 5 milliseconds as the maximal temporal
resolution of a human ear, then it corresponds to 10.24% of the
available bandwidth.
[0070] The slot-specific size can be adjusted. For example, in
audio compression, frequencies close to 20 kHz are hardly detected
by the human ear, and as such it can be expected that the frequency
content is often reduced. In this case, the slot size for
frequencies close to 4 kHz may be 2000 octets, while the slot size
for frequencies close to 20 kHz may be 256 octets, as defined by
the user. This example can be generalized to any application
utilizing a time-sensitive network to transport frequency content
that can be subdivided into sub-bands.
[0071] The time-aware scheduler device can be configured in such a
way that it drops a sample if it must be enqueued. For example, if
a talker (e.g., publishing device) is sending samples too fast for
a specific sub-band, then compression is performed by the network
itself, or, the network can be considered as a low-pass filter.
Generally, the bridge dropping a sample detects the corresponding
miss and can advertise to all the talkers that lossy compression is
being performed on a specific band.
[0072] The Ethernet frames may be at least 48 octets long
(excluding the Ethernet header). The stream ID can be used to
represent the sample or a sequence, and may use up to 8 octets. Out
of the remaining 40 octets, the peaks of 5 frequencies can be
represented in a given sub-band, with 4 octets representing the
frequency in its sub-band and 4 octets for its amplitude. If
quantization error is not damaging the quality too much,
potentially 10 frequencies can be used. Different streams may be
packed into the same frame. In this case, the identifier can be
used to make the distinction.
[0073] The media clock may not be necessary if the listening device
has a time-aware scheduler. The listening device keeps track of the
number of slots and multiplies it by the period (which equals to 5
milliseconds in our example) and then adds 156 microseconds per
band id (for instance, 1.56 milliseconds for the 10.sup.th
sub-band) to reconstruct the media clock. The audio signals may be
subject to dispersion because each of the sub-bands is slightly
delayed from each other, in our example by 156 microseconds.
Because the 156 microseconds is below the 5 millisecond maximal
temporal resolution of a human ear, the dispersion is not
noticeable.
[0074] Time-sensitive network generalized sub-band coding may be
specified utilizing a quantification of signal error. In some
use-cases, a goal is to transmit a signal in the frequency domain.
In other use-cases, a goal is to transmit a signal coded in the
frequency domain, but then to convert to the time domain upon
reception. In at least one embodiment, the scheduler device of the
time-sensitive network is configured to generate a schedule based
on a quality-of-service (QoS) requirement or constraint for
sub-band coding. For example, the QoS requirement may be an
objective function, and the scheduler device may compute an IEEE
802.1Qbv configuration that meets the required QoS requirement. The
QoS requirement may represent or may be related to the signal
fidelity target described herein.
[0075] A goal of one or more embodiments herein is to find a
generalized means of decoupling the implementation (the specific
Qbv configuration) from the QoS measurement. This is beneficial
because there may be multiple Qbv configurations that yield the
same QoS measurement. Forcing the time-sensitive network to use a
specific Qbv configuration, that is, specific frame size and
maximum latency requirements, limits the solution space of the
scheduler device when more and better solutions are available to
meet a required QoS. According to at least one embodiment, the
scheduler device is configured to generate the schedule to meet the
general QoS requirement, and is not over-constrained by having to
find a pre-ordained Qbv configuration. The scheduler device may be
allowed to pick from any of a variety of satisfactory solutions
that meet the QoS requirement. Qbv specifies data samples of a
given maximum size into periodic sampling rates over a
time-sensitive network. These may be samples from the time domain
or from the frequency domain, such as specific frequency
components. The QoS is the input to the scheduler device. The
scheduler device may be free to choose any solution that satisfies
the higher-level QoS requirements, and optionally is not given the
maximum Ethernet frame size or maximum latencies as constraints.
This decoupling may allow for a larger solution space and a better
solution. In an alternative, hybrid approach, all three of the QoS
requirement, maximum frame sizes, and maximum latencies are
utilized as constraints when scheduling the time-sensitive
network.
[0076] With regards to the selection of which QoS measurement or
requirement to use as the objective function, the QoS measurement
generally must be able to map from a set of Ethernet frame sizes
and periodic latencies (IEEE 802.1Qbv configuration) into a
received signal quality. One option is to use the power spectral
density (PSD), which describes the distribution of the average
power of a signal over its frequency components. The PSD might be
useful in specifying the QoS in the frequency domain or estimating
how well the time domain was reconstructed after transmission.
Another option is to use mean opinion scores, which have been used
for human sensual input, both audio and visual. A third option is
to use peak signal-to-noise ratio (PSNR), which can be automated to
estimate video quality.
[0077] In an embodiment, a vehicle communication system includes
multiple nodes of a time-sensitive network disposed onboard plural
vehicles, and a scheduler device. The nodes are communicatively
connected to each other via wired and/or wireless links. At least
one of the nodes is configured to obtain a first signal from a
publishing device. The first signal is represented in a frequency
domain by multiple frequency components. The scheduler device
(e.g., comprising one or more processors) is configured to generate
a schedule for transmission of signals including the first signal
within the time-sensitive network. The schedule defines multiple
slots assigned to different discrete frequency sub-bands within a
frequency band. The slots have designated transmission intervals.
The nodes are configured to transmit the first signal through the
time-sensitive network to a listening device such that the first
signal is received at the listening device within a designated time
window according to the schedule. At least some of the frequency
components of the first signal are transmitted through the
time-sensitive network within different slots of the schedule based
on the frequency sub-bands assigned to the slots. In one aspect,
the plural vehicles are mechanically connected to one another,
e.g., the vehicles may be rail vehicles in a train. In another
embodiment, the vehicles are not mechanically connected to one
another, but are configured to wirelessly communicate signals over
the network for coordinated control for movement together along a
route.
[0078] In one embodiment, a communication system includes a
scheduler device including one or more processors configured to
generate a schedule for communication of signals through nodes of a
time-sensitive network that are communicatively connected to each
other via links of the time-sensitive network. At least a first
signal of the signals is represented in a frequency domain by
multiple frequency components and received into the time-sensitive
network from a publishing device. The one or more processors are
configured to generate the schedule by assigning multiple slots
having designated transmission intervals to different discrete
frequency sub-bands within a frequency band. The schedule is
generated to direct the nodes to communicate the first signal from
the publishing device through the time-sensitive network to a
listening device such that the first signal is received at the
listening device within a designated time window according to the
schedule. At least some of the frequency components of the first
signal are transmitted through the time-sensitive network based on
the frequency sub-bands assigned to the slots.
[0079] Optionally, the one or more processors are configured to
generate the schedule to direct the nodes to transmit a first
frequency component of the first signal within a first slot of the
slots that is assigned to a frequency sub-band that contains a
frequency of the first frequency component, and to transmit a
second frequency component of the first signal within a second slot
of the slots that is assigned to a different frequency sub-band
that contains a frequency of the second frequency component.
[0080] Optionally, the one or more processors are configured to
determine a designated signal fidelity target that represents a
degree of correspondence between an exit state of the first signal
exiting the time-sensitive network at the listening device and an
entry state of the first signal entering the time-sensitive network
at the publishing device. The one or more processors can be
configured to generate the schedule to assign the slots to at least
a number of the frequency sub-bands associated with the designated
signal fidelity target.
[0081] Optionally, the one or more processors are configured to
generate the schedule based on the designated signal fidelity
target without utilizing a frame size limit or a periodic latency
limit as a constraint to the schedule.
[0082] Optionally, the one or more processors are configured to
generate the schedule to assign less than all the frequency
sub-bands of the frequency band to the slots. The nodes can be
configured to filter out one or more of the frequency components of
the first signal having a frequency outside of the frequency
sub-bands by transmitting only the frequency components of the
first signal having frequencies within the frequency sub-bands
assigned to the slots.
[0083] Optionally, the one or more processors are configured to
generate the schedule to stagger the transmission intervals of the
slots such that a first frequency component of the first signal
within a first slot is transmitted by the nodes of the
time-sensitive network according to the schedule at different times
than the nodes transmit a second frequency component of the first
signal within a second slot.
[0084] Optionally, the frequency components of the first signal are
encoded within Ethernet frames. The Ethernet frames can include
data representing one or more of a frequency, an amplitude, or a
phase of each of the frequency components encoded therein.
[0085] Optionally, the first signal is one or more of an audio
signal, an ultrasound signal, a vibration signal, an audible sound
signal, and/or an infrasound signal.
[0086] Optionally, the one or more processors are configured to
generate or modify the schedule by changing a size of the frequency
sub-band assigned to one or more of the slots after the first
signal is transmitted through the time-sensitive network.
[0087] In one embodiment, a method includes generating a schedule
for transmission of signals within a time-sensitive network. The
schedule defines multiple slots assigned to different discrete
frequency sub-bands within a frequency band and the slots have
designated transmission intervals. The method also includes
obtaining a first signal of the signals from a publishing device.
The first signal is represented in a frequency domain by multiple
frequency components. The method also includes transmitting the
first signal through the time-sensitive network to a listening
device such that the first signal is received at the listening
device within a designated time window according to the schedule.
At least some of the frequency components of the first signal are
transmitted through the time-sensitive network within different
slots of the schedule based on the frequency sub-bands assigned to
the slots.
[0088] Optionally, transmitting the first signal through the
time-sensitive network includes transmitting a first frequency
component of the first signal within a first slot of the schedule
assigned to a frequency sub-band that contains a frequency of the
first frequency component, and transmitting a second frequency
component of the first signal within a second slot of the schedule
assigned to a different frequency sub-band that contains a
frequency of the second frequency component.
[0089] Optionally, the method also includes obtaining a designated
signal fidelity target that represents correspondence between an
exit state of the first signal exiting the time-sensitive network
at the listening device and an entry state of the first signal
entering the time-sensitive network at the publishing device.
Generating the schedule may include assigning the slots to a
sufficient number of the frequency sub-bands to satisfy the
designated signal fidelity target.
[0090] Optionally, the schedule is generated based on the
designated signal fidelity target without utilizing a frame size
limit or a periodic latency limit as a constraint on the
schedule.
[0091] Optionally, the frequency sub-bands assigned to the slots
defined by the schedule represent less than an entirety of the
frequency band. Transmitting the first signal can include
transmitting only the frequency components of the first signal
having frequencies within the frequency sub-bands assigned to the
slots to filter out one or more of the frequency components of the
first signal having a frequency outside of the frequency
sub-bands.
[0092] Optionally, generating the schedule comprises staggering the
transmission intervals of the slots such that a first frequency
component of the first signal within a first slot is transmitted by
the nodes of the time-sensitive network according to the schedule
at different times than the nodes transmit a second frequency
component of the first signal within a second slot.
[0093] Optionally, the frequency components of the first signal are
encoded within Ethernet frames, and the Ethernet frames can include
data representing one or more of a frequency, an amplitude, and/or
a phase of each of the frequency components encoded therein.
[0094] Optionally, the first signal is one or more of an audio
signal, an ultrasound signal, a vibration signal, an audible sound
signal, and/or an infrasound signal.
[0095] Optionally, the method also includes combining the frequency
components of the first signal after transmitting the frequency
components through the time-sensitive network to provide an intact
first signal to the listening device.
[0096] In one embodiment, a communication system includes a
scheduler device including one or more processors configured to
generate a schedule for communication of signals through nodes of a
time-sensitive network that are communicatively connected to each
other via links of the time-sensitive network. At least a first
signal of the signals is represented in a frequency domain by
multiple frequency components and received into the time-sensitive
network from a publishing device. The one or more processors are
configured to generate the schedule by assigning multiple slots
having designated transmission intervals to different discrete
frequency sub-bands within a frequency band. The schedule is
generated to direct the nodes to communicate the frequency
components of the first signal through the time-sensitive network
based on the frequency sub-bands assigned to the slots such that
the nodes transmit a first frequency component of the first signal
within a first slot of the slots that is assigned to a frequency
sub-band that contains a frequency of the first frequency component
and the nodes transmit a second frequency component of the first
signal within a second slot of the slots that is assigned to a
different frequency sub-band that contains a frequency of the
second frequency component.
[0097] Optionally, the one or more processors are configured to
generate or modify the schedule by changing a size of the frequency
sub-band assigned to one or more of the slots after the first
signal is transmitted through the time-sensitive network.
[0098] In an embodiment, a rail vehicle communication system is
provided that includes multiple nodes of a time-sensitive network
and a scheduler device. The time-sensitive network is disposed
onboard one or more locomotives. The nodes are communicatively
connected to each other via links. At least one of the nodes is
configured to obtain a first signal from a publishing device. The
first signal is represented in a frequency domain by multiple
frequency components. The scheduler device comprises one or more
processors and is configured to generate a schedule for
transmission of signals including the first signal within the
time-sensitive network. The schedule defines multiple slots
assigned to different discrete frequency sub-bands within a
frequency band. The slots have designated transmission intervals.
The nodes are configured to transmit the first signal through the
time-sensitive network to a listening device such that the first
signal is received at the listening device within a designated time
window according to the schedule. At least some of the frequency
components of the first signal are transmitted through the
time-sensitive network within different slots of the schedule based
on the frequency sub-bands assigned to the slots.
[0099] Optionally, the nodes are configured to transmit a first
frequency component of the first signal within a first slot of the
schedule assigned to a frequency sub-band that contains a frequency
of the first frequency component, and the nodes transmit a second
frequency component of the first signal within a second slot of the
schedule assigned to a different frequency sub-band that contains a
frequency of the second frequency component.
[0100] Optionally, the scheduler device is configured to obtain a
designated signal fidelity target that represents a degree of
correspondence between a state of the first signal exiting the
time-sensitive network at the listening device and a state of the
first signal entering the time-sensitive network at the publishing
device. The scheduler device generates the schedule to assign the
slots to a sufficient number of the frequency sub-bands to satisfy
the designated signal fidelity target. Optionally, the scheduler
device is configured to generate the schedule based on the
designated signal fidelity target without utilizing a frame size
limit or a periodic latency limit as a constraint.
[0101] Optionally, the frequency sub-bands assigned to the slots
defined by the schedule represent less than an entirety of the
frequency band. The nodes are configured to transmit only the
frequency components of the first signal having frequencies within
the frequency sub-bands assigned to the slots to filter out one or
more of the frequency components of the first signal having a
frequency outside of the frequency sub-bands.
[0102] Optionally, the scheduler device is configured to generate
the schedule to stagger the transmission intervals of the slots
such that a first frequency component of the first signal within a
first slot is transmitted by nodes of the time-sensitive network
according to the schedule at different times than the nodes
transmit a second frequency component of the first signal within a
second slot.
[0103] Optionally, the frequency components of the first signal are
encoded within Ethernet frames, and the Ethernet frames include
data representing a frequency, an amplitude, and/or a phase of each
of the frequency components encoded therein.
[0104] Optionally, the first signal is an audio signal, an
ultrasound signal, a vibration signal, an audible sound signal,
and/or an infrasound signal.
[0105] Optionally, the first signal represents a measurement of a
component onboard a first locomotive of the one or more
locomotives.
[0106] Optionally, the scheduler device is further configured to
modify a size of the frequency sub-band assigned to one or more of
the slots after the first signal is transmitted through the
time-sensitive network.
[0107] In an embodiment, a method for locomotive communications is
provided that includes generating a schedule for transmission of
signals within a time-sensitive network onboard one or more
locomotives. The schedule defines multiple slots assigned to
different discrete frequency sub-bands within a frequency band. The
slots have designated transmission intervals. The method includes
obtaining a first signal of the signals from a publishing device.
The first signal is represented in a frequency domain by multiple
frequency components. The method also includes transmitting the
first signal through the time-sensitive network to a listening
device such that the first signal is received at the listening
device within a designated time window according to the schedule.
At least some of the frequency components of the first signal are
transmitted through the time-sensitive network within different
slots of the schedule based on the frequency sub-bands assigned to
the slots.
[0108] Optionally, transmitting the first signal through the
time-sensitive network includes transmitting a first frequency
component of the first signal within a first slot of the schedule
assigned to a frequency sub-band that contains a frequency of the
first frequency component, and transmitting a second frequency
component of the first signal within a second slot of the schedule
assigned to a different frequency sub-band that contains a
frequency of the second frequency component.
[0109] Optionally, the method also includes obtaining a designated
signal fidelity target that represents a degree of correspondence
between a state of the first signal exiting the time-sensitive
network at the listening device and a state of the first signal
entering the time-sensitive network at the publishing device.
Generating the schedule comprises assigning the slots to a
sufficient number of the frequency sub-bands to satisfy the
designated signal fidelity target. Optionally, the schedule is
generated based on the designated signal fidelity target without
utilizing a frame size limit or a periodic latency limit as a
constraint.
[0110] Optionally, the frequency sub-bands assigned to the slots
defined by the schedule represent less than an entirety of the
frequency band. Transmitting the first signal comprises
transmitting only the frequency components of the first signal
having frequencies within the frequency sub-bands assigned to the
slots to filter out one or more of the frequency components of the
first signal having a frequency outside of the frequency
sub-bands.
[0111] Optionally, generating the schedule comprises staggering the
transmission intervals of the slots such that a first frequency
component of the first signal within a first slot is transmitted by
nodes of the time-sensitive network according to the schedule at
different times than the nodes transmit a second frequency
component of the first signal within a second slot.
[0112] Optionally, the frequency components of the first signal are
encoded within Ethernet frames, and the Ethernet frames includes
data representing a frequency, an amplitude, and/or a phase of each
of the frequency components encoded therein.
[0113] Optionally, the first signal is an audio signal, an
ultrasound signal, a vibration signal, an audible sound signal,
and/or an infrasound signal.
[0114] Optionally, the method also includes combining the frequency
components of the first signal after transmitting the frequency
components through the time-sensitive network to provide an intact
first signal to the listening device.
[0115] Optionally, the first signal represents a measurement of a
component onboard a first locomotive of the one or more
locomotives.
[0116] Optionally, the method also includes modifying a size of the
frequency sub-band assigned to one or more of the slots after
transmitting the first signal through the time-sensitive
network.
[0117] As used herein, an element or step recited in the singular
and proceeded with the word "a" or "an" should be understood as not
excluding plural of said elements or steps, unless such exclusion
is explicitly stated. Furthermore, references to "one embodiment"
of the presently described subject matter are not intended to be
interpreted as excluding the existence of additional embodiments
that also incorporate the recited features. Moreover, unless
explicitly stated to the contrary, embodiments "comprising,"
"including," and "having" an element or a plurality of elements
with a particular property may include additional such elements not
having that property.
[0118] It is to be understood that the above description is
intended to be illustrative, and not restrictive. For example, the
above-described embodiments (and/or aspects thereof) may be used in
combination with each other. In addition, many modifications may be
made to adapt a particular situation or material to the teachings
of the subject matter set forth herein without departing from its
scope. While the dimensions and types of materials described herein
are intended to define the parameters of the disclosed subject
matter, they are by no means limiting and are example embodiments.
Many other embodiments will be apparent to those of ordinary skill
in the art upon reviewing the above description. The scope of the
subject matter described herein should, therefore, be determined
with reference to the appended claims, along with the full scope of
equivalents to which such claims are entitled. In the appended
claims, the terms "including" is used as the plain-English
equivalents of the term "comprising." Moreover, in the following
claims, the terms "first," "second," and "third," etc. are used
merely as labels, and are not intended to impose numerical
requirements on their objects. Further, the limitations of the
following claims are not written in means-plus-function format and
are not intended to be interpreted based on 35 U.S.C. .sctn.
112(f), unless and until such claim limitations expressly use the
phrase "means for" followed by a statement of function void of
further structure.
* * * * *